Technical Field
The present invention relates to a radical polymerizable composition, a radical polymerizable coating, a radical polymerizable ink, an ink cartridge containing the ink, a coating method and a coated matter.
Description of the Related Art
PCT Japanese published national phase application No. 2004-526820 discloses a widely-known photopolymerizable composition such as a photopolymerizable inkjet ink using (meth)acrylic acid ester. Japanese published unexamined application No. JP-2013-181114-A discloses a coating liquid having such a viscosity as to easily be dischargeable from a nozzle head or a spray gun, and capability of firmly protecting a substrate.
It is known that a material having a siloxane chain structure is used as a material of an inkjet ink composition. For example, Japanese published unexamined application No. JP-2008-248220-A discloses polyester-modified or polyether-modified silicone is added to an inkjet ink as a surfactant to disperse a nonaqueous resin emulsion in alkylene glycol as an organic solvent. Japanese published unexamined application No. JP-2010-161186-A discloses adding polyether-modified silicone and/or fluorine-containing ethylene compound as a lubricant to a photopolymerizable composition for forming a transfer sheet having good releasability from a mold having a microscopic concave and convex patterns. Further, in order to prevent an inkjet ink from penetrating in a paper substrate and swelling the substrate to curl, Japanese published unexamined application No. JP-2012-207202-A discloses an inkjet ink including polyol having an equilibrium water content not greater than 30% at TH 80%, amide compound having the following formula:R.OCH2.CH2.CO.N(Me)2 wherein R Represents an alkyl group having 4 to 6 carbon atoms,a liquid compound having a specific ether structure and/or a specific dicarboxylic acid ester structure, and a fluorine-containing surfactant and/or a polyether modified silicone surfactant.
In terms of protecting the surface of a substrate, sufficiently high coating strength is one of important functions.
For examples, (meth)acrylate materials having polyurethane skeletons are marketed. Some of them are said to be suitable for hard coat applications and have very high surface hardness in pencil hardness test of JIS standard mentioned later. However, they unexceptionally have very high viscosities of from some ten to hundred thousands Pa·s, and a photopolymerizable composition supposed to be used even in an inkjet ink, having a practical range of low viscosity can scarcely include them in fact. Further, polyurethane including many nitrogen atoms in its molecule noticeably becomes yellowish as time passes.
Not only when the photopolymerizable composition is used for spray coating or bar coating, but also when used for an inkjet ink, unless raw materials of the photopolymerizable composition, i.e., monomer materials have sufficiently low viscosity, the photopolymerizable composition is difficult to have a practical range of low viscosity.
A dilution solvent enables the photopolymerizable composition to have low viscosity. It is preferable not to add a solvent to the photopolymerizable composition in consideration of bad influence of the volatilized solvent against environment. Water enables the photopolymerizable composition to have low viscosity as well using a hydrosoluble monomer. However, penetration drying cannot be expected from a plastic substrate and water needs volatilizing when print coating process is accelerated, which typically needs an unpreferable heat source unpreferable in terms of saving energy.